Vehicular air-conditioning system

ABSTRACT

A heating-use heat exchanger which includes a first heater core which exchanges heat between a first liquid and air blown into a passenger compartment and a second heater core which exchanges heat between a second liquid which is higher in temperature and smaller in flow rate than the first liquid and blown air which is heated by the first heater core is held in an air-conditioning case so that an inlet side tank part is at the bottom and an exit side tank part is at the top and the tube longitudinal direction is slanted. Due to this, the high temperature second liquid flowing into the second heater core is stored inside of the inlet side tank part in a region above the tube inlet side ends over the entire stacking direction of the plurality of tubes, then flows into the plurality of tubes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicular air-conditioning systemcomprising a heating-use heat exchanger which heats air which is blowninto a passenger compartment.

2. Description of the Related Art

As such vehicular air-conditioning systems, there are the ones describedin U.S. Pat. No. 5,337,704 and European Patent Application PublicationNo. 1008471.

In the system described in U.S. Pat. No. 5,337,704, as cooling waterchannels inside of the engine, there are the cylinder head-side channelwhich cools the cylinder head and the cylinder block-side channel whichcools the cylinder block. The cooling water which passes through thecylinder head-side channel is designed to flow into a single heating-useheat exchanger.

In the system described in European Patent Application Publication No.1008471, two heating-use heat exchangers are provided for heating air.The cooling water which flows out from a single cooling water exit whichis provided at the engine is branched and made to flow to theheating-use heat exchangers.

SUMMARY OF THE INVENTION

In this regard, in recent years, the engines which are mounted invehicles are being required to secure the required output while beingmade smaller in size. If realizing this by raising the compression ratioor raising supercharging pressure in a supercharged engine, knocking isliable to occur, so it is necessary to improve the anti-knockingperformance. Therefore, to improve the anti-knocking performance, it maybe considered to positively cool the cylinder head.

However, to suppress an increase in friction inside of the engine forthe cylinder block, it is necessary to maintain a predeterminedtemperature or more. For this reason, as the cooling water channelinside of the engine, it may be considered to provide a cylinderhead-side channel and a cylinder block-side channel and make the coolingwater flow rate of the cylinder head-side channel greater than thecooling water flow rate of the cylinder block-side channel.

However, in this case, the cooling water temperature after cooling thecylinder head becomes lower than the minimum temperature required forheating. As shown in the art described in U.S. Pat. No. 5,337,704, ifheating the air blown into the passenger compartment using as a heatsource only the cooling water which cooled the cylinder head, theproblem arises that the air temperature cannot be sufficiently raised.Note that, in the past, the cooling water temperature after cooling thecylinder head was 80 to 90° C. This exceeded the minimum temperaturerequired for heating, so this problem did not arise.

Therefore, as a heating-use heat exchanger, one may be considered whichincludes a first heat exchange part which exchanges heat between thecooling water which cooled the cylinder head and the blown air, and asecond heat exchange part which exchanges heat between the cooling,water which cooled the cylinder block and the blown air which was heatedat the first heat exchange part.

According to this, the first heat exchange part uses the cooling waterwhich cooled the cylinder block as the heat source to heat the blownair, then the second heat exchange part uses the cooling water aftercooling the cylinder block, which is higher in temperature than thecooling water after cooling the cylinder head, as the heat source tofurther heat the blown air which was heated by the first heat exchangepart, so it is possible to sufficiently raise the air temperature afterpassing through the heating-use heat exchanger.

However, in this case, the cooling water flow rate of the cylinderblock-side channel is smaller than the cooling water flow rate of thecylinder head-side channel, so the cooling water which flows into thesecond heat exchange part becomes smaller in flow rate than the coolingwater which flows into the first heat exchange part. For this reason, asexplained above, it was learned that in the air-conditioned air afterpassing through the heating-use heat exchanger, a temperaturedistribution ends up forming with a large temperature difference in theleft-right direction.

That is, the second heat exchange part comprises a plurality of tubeswhich are stacked together, an inlet side tank part which is connectedto first end sides of the plurality of tubes in a longitudinal directionthereof and which forms a cooling water inlet side, and an exit sidetank part which is connected to the other end sides of the plurality oftubes in the longitudinal direction thereof and which forms a coolingwater exit side. It was learned that when having the second heatexchange part held at the air-conditioning case so that the inlet sidetank part is positioned at the bottom side and the exit side tank partis positioned at the top side and the cooling water flows from thebottom to the top inside of the second heat exchange part, thephenomenon ends up arising that most of the cooling water which flowsinto the inlet side tank part flowing through the tubes close to thecooling water inlet and the cooling water has a hard time flowing up tothe tubes far from the cooling water inlet.

This is due to the following reason. In general, when there is a hightemperature part at the bottom side of the inside of a liquid, that hightemperature part rises due to its buoyancy. Further, in the second heatexchange part, the cooling water flows through the inside of the tubeswhile exchanging heat with the air. The cooling water which flows intothe inlet side tank part is higher in temperature than the cooling waterinside of the exit side tank part. For this reason, the high temperaturecooling water which flows into the inlet side tank part is affected bybuoyancy. Furthermore, if the cooling water which flows into the secondheat exchange part becomes a low flow velocity of a flow rate smallerthan the cooling water which flows into the first heat exchange part,this effect of buoyancy becomes further larger.

If the air-conditioned air after passing through the heating-use heatexchanger ends up with a temperature distribution with a largetemperature difference in the left-right direction, for example, theair-conditioned air after passing through the heating-use heat exchangerends up branching to one side and the other side in the vehicleleft-right direction. When air-conditioned air is blown out from adriver-side vent and a passenger-side vent, a difference ends up arisingin the vented air temperature at the driver's side and the passenger'sside.

Note that, such a problem is not limited to the case where the firstheat exchange part uses the cooling water after cooling the cylinderhead as a heat source and where the second heat exchange part uses thecooling water after cooling the cylinder block as a heat source. It is aproblem which arises when the first heat exchange part uses a firstliquid as a heat source and when the second heat exchange part uses asecond liquid with a temperature higher than and flow rate smaller thanthe first liquid as a heat source.

The present invention is made in consideration of the above point andhas as its object the provision of a vehicular air-conditioning systemwhich can reduce the temperature difference in the left-right directionwhich occurs in air-conditioned air after passing through a heating-useheat exchanger.

To achieve this object, a first aspect of the present invention providesa vehicular air-conditioning system wherein a second heat exchange part(20) stores a second liquid which flows into an inlet side tank part(22) and which is higher in temperature than a liquid in an exit sidetank part (23) inside of liquid storage parts (71, 72, 73, 74) inside ofan inlet side tank part across an entire stacked direction of theplurality of tubes (21), then runs it into the plurality of tubes (21).

According to the present invention, by employing such a constitution,even if the second liquid which flows through the second heat exchangepart is lower in flow velocity than the first liquid which flows throughthe first heat exchange part, it is possible to reduce the temperaturedifference of the cooling water which flows through the plurality oftubes and possible to reduce the temperature difference in theleft-right direction occurring in air-conditioned air after passingthrough the heating-use heat exchanger.

In the present invention, the second heat exchange part (20) may be madeto slant so as to form a liquid storage part (71) at the inside of theinlet side tank part (22) in a region above inlet side ends (21 a) ofthe tubes (21).

Further, in the present invention, part of a wall (91) forming the inletside tank part (22) may be made to bulge outward from the other parts soas to form a liquid storage part (72).

Further, in the present invention, an insertion length (84) of tubes(21) which are inserted at an inlet side tank part (22) of the secondheat exchange part (20) may be made longer than an insertion length (85)of tubes (11) which are inserted at the inlet side tank part (12) of thefirst heat exchange part (20) so as form a liquid storage part (74) inthe inside of the inlet side tank part (22) of the second heat exchangepart (10) in a region above the inlet side ends (21 a) of the tubes (21)in the gravity direction.

In this regard, when projecting the end opening (20 a) of a liquidintroduction path in the inlet side tank part (22) of the second heatexchange part (20) in a longitudinal direction of the inlet side tankpart (22), if the end opening (20 a) of the liquid introduction path ispositioned right under the inlets of the tubes (21), the hightemperature liquid which flows into the inlet side tank part rises dueto buoyancy, so when high temperature liquid flows into the inlet sidetank part, the high temperature liquid ends up flowing into the tubespositioned above inflowing liquid.

Therefore, in the present invention, at least part of the end opening(20 a) of the liquid introduction path is preferably positioned at aposition other than right under the inlets of the tubes (21) in thegravity direction.

According to this, part of the end opening of the liquid introductionpath is outside from the range right under the tubes, so it is possibleto reliably guide part of the high temperature second liquid whichflowed in from the end opening of the liquid introduction path to theliquid storage part.

As the constitution where at least part of the end opening (20 a) of theliquid introduction path is positioned other than right under the inletsof the tubes (21), the present invention can employ a constitution whereat least part of the end opening (20 a) of the liquid introduction pathis positioned outside from between two imaginary lines (81, 82) whichare drawn from the inner walls (21 b) of the tubes (21) at the inletside ends (21 a) of the tubes (21) in parallel in the gravity direction.Further, it is also possible to employ a constitution in which at leastpart of the end opening (20 a) of the liquid introduction path ispositioned above an imaginary line (83) which passes through the inletside end faces (21 a) of the tubes (21). Note that, it is also possibleto employ both the configurations.

Further, in the present invention, a part of 35% or more of the totalarea of the end opening (20 a) of the liquid introduction path ispreferably positioned other than right under the inlets of the tubes(21) in the gravity direction. Due to this, it is possible toparticularly reduce the temperature difference of the left-right ventedair from the heating-use heat exchanger as shown in the later explainedFIG. 10.

Further, in the present invention, the second heat exchange part (20) ispreferably mounted in a vehicle in a slanted state so that the secondliquid flows in from one end side of the inlet side tank part (22) inthe longitudinal direction thereof and so that the top wall of the inletside tank part (22) is arranged with a first end side of the inlet sidetank part (22) in the longitudinal direction positioned above the otherend side in the longitudinal direction in the gravity direction. Due tothis, compared with the case where the top wall of the inlet side tankpart is horizontal, it is possible to easily guide the high temperatureliquid which flows through the liquid storage part to the first end sideof the inlet side tank part in the longitudinal direction.

Further, in the present invention, inside of the inlet side tank part(22) of the second heat exchange part (20), it is also possible toprovide a flow velocity raising means (92) for raising the flow velocityof the second liquid which flows to the inlet side tank part (22).

According to this, it is possible to raise the flow velocity of thesecond liquid which flows into the inlet side tank part after passingthrough the flow velocity raising means (92) compared with beforepassing, so compared with the case of not providing means for raisingthe flow velocity of the cooling water, it is possible to run coolingwater until the side of the inlet side tank part away from the secondliquid inlet. Accordingly, according to the present invention, comparedwith the case of forming the liquid storage part, Furthermore, it ispossible to reduce the temperature difference of the cooling water whichflows through the plurality of tubes and possible to reduce thetemperature difference in the left-right direction occurring in theair-conditioned air after passing through the heating-use heatexchanger.

Further, in the present invention, it is possible to make the channelsectional area of the inlet side tank part (22) of the second heatexchange part (20) smaller than that of the first heat exchange part(10), possible to make the channel sectional area of a liquidintroduction path which introduces the second liquid to the inlet sidetank part (22) of the second heat exchange part (20) smaller than thatof the first heat exchange part (10), and possible to adopt bothconstitutions.

In this way, by raising the flow velocity of the second liquid whichflows into the inlet side tank part, it is possible to run cooling waterup to the side of the inlet side tank part away from the second liquidinlet.

Further, a second aspect of the present invention provides a vehicularair-conditioning system which provides, at the inside of the inlet sidetank part (22) of the second heat exchange part (20), a flow velocityraising means (92) for raising the flow velocity of the second liquidwhich flows into the inlet side tank part (22).

According to this, it is possible to raise the flow velocity of thesecond liquid which flows into the inlet side tank part after passingthrough the flow velocity raising means (92) compared with beforepassing through it, so compared with the case of not providing means forraising the flow velocity of the cooling water, it is possible to runthe cooling water to the side of the inlet side tank part away from thesecond liquid inlet. Accordingly, according to the present invention, itis possible to reduce the temperature difference of the cooling waterflowing through the plurality of tubes and possible to reduce thetemperature difference in the left-right direction occurring in theair-conditioned air after passing through the heating-use heatexchanger.

In the present invention, the flow velocity of the second liquid whichflows through the inlet side tank part (22) of the second heat exchangepart (20) is preferably made the same or equal to the flow velocity ofthe first liquid which flows through the inlet side tank part (12) ofthe first heat exchange part (10).

Note that the reference signs in parentheses after the means describedin this section and the claims show the correspondence with specificmeans described in the embodiments explained later.

The present invention may be more fully understood from the descriptionof preferred embodiments of the invention, as set forth below, togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view of the configuration of a vehicularair-conditioning system of a first embodiment;

FIG. 2 is a side view of a heating-use heat exchanger in FIG. 1 in thestate held in an air-conditioning case;

FIG. 3 is a front view of the heating-use heat exchanger in FIG. 1;

FIG. 4 is a front view of a second heater core showing the flow ofcooling water in the first embodiment;

FIG. 5 is a front view of a second heater core showing the flow ofcooling water in Comparative Example 1;

FIG. 6 is a cross-sectional view of a heating-use heat exchanger in asecond embodiment;

FIG. 7 is a cross-sectional view of a heating-use heat exchanger in athird embodiment;

FIG. 8 is a side view of a heating-use heat exchanger 2 for explaining aslant angle θ1 of the second heater core 20 in the third embodiment;

FIG. 9 is a view showing the relationship between a temperaturedifference of left-right vented air from the heating-use heat exchanger2 and the slant angle θ1 shown in FIG. 8;

FIG. 10 is a view showing the relationship between the temperaturedifference of left and right vented air from the heating-use heatexchanger 2 and the ratio of an area of a part at a position other thanright under the inlets of the tubes 21 with respect to the total area ofthe cooling water inlet 20 a;

FIG. 11 is a cross-sectional view of a heating-use heat exchanger in afourth embodiment;

FIG. 12 is a cross-sectional view of a heating-use heat exchanger in afifth embodiment;

FIG. 13 is a cross-sectional view of a heating-use heat exchanger in asixth embodiment;

FIG. 14 is a front view of a heating-use heat exchanger in a seventhembodiment;

FIG. 15 is a view showing the relationship of the slant angle θ2 of theheating-use heat exchanger in the seventh embodiment and the left-rightvented air temperature difference;

FIG. 16 is a cross-sectional view of a heating-use heat exchanger in aneighth embodiment;

FIG. 17 is a cross-sectional view of a heating-use heat exchanger in aninth embodiment;

FIG. 18A is a side view of a heating-use heat exchanger in a 10thembodiment;

FIG. 18B is a front view of the heating-use heat exchanger in the 10thembodiment; and FIG. 19 is a side view of a heating-use heat exchangerin an 11th embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, embodiments of the present invention will be explained based onthe drawings. Note that, in the following embodiments, the same orequivalent parts are assigned the same reference signs and explanationsare omitted.

First Embodiment

FIG. 1 shows the schematic configuration of a vehicular air-conditioningsystem in the present embodiment. The vehicular air-conditioning systemof the present embodiment is mounted in a hybrid vehicle which obtainsdrive power for driving the vehicle from an engine (internal combustionengine) and driving-use electric motor.

The vehicular air-conditioning system 1 of the present embodiment isprovided with a heating-use heat exchanger 2 which exchanges heatbetween cooling water of an engine 30 and air blown into a passengercompartment so as to heat the air blown into the passenger compartment.Note that, the cooling water is water or water containing addedingredients.

The heating-use heat exchanger 2 has a first heater core 10 and a secondheater core 20. The two are integrally formed. The first heater core 10and the second heater core 20 respectively correspond to the first heatexchange part and the second heat exchange part of the heating-use heatexchanger in the present invention.

The first heater core 10 is run through by cooling water which cooledthe cylinder head 31 of the engine 30, while the second heater core 20is run through by cooling water which cooled the cylinder block 32 ofthe engine 30. The first heater core 10 is positioned at the upstreamside in the air flow, while the second heater core 20 is positioned atthe downstream side in the air flow.

Here, in the engine 30, the cylinder block 32 is a block member whichforms cylinder bores (columnar holes) through which pistons movereciprocatively. The cylinder head 31 is a block member which closes theopenings at the top dead center side of the cylinder bores so as to formcombustion chambers.

At the cylinder head 31 side of the engine 30, a first cooling waterinlet 31 a and a first exit part comprised of a first cooling water exit31 b are provided. Inside of the cylinder head 31, a cylinder head-sidecooling water channel through which cooling water which cools thecylinder head 31 flows is formed. The cooling water which flows from thefirst cooling water inlet 31 a flows through the inside of the cylinderhead 31, then flows out from the first cooling water exit 31 b.

In the same way, at the cylinder block 32 side of the engine 30, asecond cooling water inlet 32 a and a second exit part comprised of asecond cooling water exit 32 b are provided. Inside of the cylinderblock 32, a cylinder block-side cooling water channel through whichcooling water which cools the cylinder block 32 flows is formed. Thecooling water which flowed from the second cooling water inlet 32 aflows through the inside of the cylinder block 32, then flows out fromthe second cooling water exit 32 b. In this way, in the presentembodiment, the cooling water which cooled the cylinder block 32 flowsout from the second cooling water exit 32 b without merging with thecooling water which cooled the cylinder head 31.

In this way, the engine 30 of the present embodiment has two coolingsystems. Further, at the time of steady operation of the engine 30, thecooling water flow rate of the cylinder head-side cooling water channelis made larger than the cooling water flow rate of the cylinderblock-side cooling water channel so as to cool the cylinder head 31 morepositively than the cylinder block 32. This is to make the cylinder head31 lower in temperature so as to improve the anti-knocking performanceand to maintain the cylinder block 32 at a high temperature to maintainthe low viscosity of the engine oil so as to suppress the increase infriction inside of the engine.

In the heating-use heat exchanger 2, the cooling water inlet 10 a of thefirst heater core 10 is connected through a pipeline to the firstcooling water exit 31 b at the cylinder head 31 side of the engine 30.The cooling water which flows out from the first cooling water exit 31 bflows to the first heater core 10. On the other hand, the cooling waterinlet 20 a of the second heater core 20 is connected through a pipelineto a second cooling water exit 32 b at the cylinder block 32 side of theengine 30. The cooling water which flows out from the second coolingwater exit 32 b flows into the second heater core 20.

Therefore, in the present embodiment, low temperature, large flow ratecooling water flows into the first heater core 10, while hightemperature, small flow rate cooling water flows into the second heatercore 20. Specifically, the temperature and flow rate of the coolingwater which flows into the first heater core 10 are 30 to 60° C. and 5to 15 L/min in range, while the temperature and flow rate of the coolingwater which flows into the second heater core 20 are 40 to 90° C. and0.2 to 3 L/min in range.

The first heater core 10 and the second heater core 20, as explainedlater, have independent heat exchange core parts. For this reason, thecooling water which flows into the first heater core 10 exchanges heatwith the air at the heat exchange care part of the first heater core 10without being mixed with the cooling water which flows into the secondheater core 20. In the same way, the cooling water which flows into thesecond heater core 20 exchanges heat with the air at the heat exchangecore part of the second heater core 20 without being mixed with thecooling water which flows into the first heater core 10. Further, theflows of cooling water which passed through the heat exchange core partsare merged, then flows out from a common cooling water exit 2 b providedat the heating-use heat exchanger 2.

The cooling water flowing out from the cooling water exit 2 b of theheating-use heat exchanger 2 is branched at the branching part 41 andthen flows to the first cooling water inlet 31 a and the second coolingwater inlet 32 a of the engine 30.

As shown in FIG. 1, a water pump 42 is arranged in the middle of thecooling water channel between the cooling water exit 2 b of theheating-use heat exchanger 2 and the branching part 41. The water pump42 is a means which forms a flow of cooling water and an adjusting meansfor adjusting the cooling water flow rate. The water pump 42 is anelectric pump. A not shown control device is used to control its speedto thereby control the cooling water flow rate.

Note that, the engine 30 is communicated with a not shown radiator.Cooling water which flow out from the cylinder head 31 radiates heat atthe radiator. After radiating heat, the cooling water can flow into thecylinder head 32. The cooling water which flow out from the cylinderblock 32 radiates heat at the radiator. After radiating heat, thecooling water can flow to the cylinder block 32.

Next, details of the heating-use heat exchanger 2 will be explained.FIG. 2 shows a side view of a heating-use heat exchanger 2 in the stateheld at an air-conditioning case 51, while FIG. 3 is a front view of theheating-use heat exchanger 2 as seen from the downstream side of the airflow. Note that, the up and down direction arrows in the figures showthe up-down direction parallel to the gravity direction in the statemounted on a vehicle. The same is true for other drawings. The vehicleat this time is positioned on a horizontal surface, not a slantedsurface.

As shown in FIGS. 2 and 3, the first and second heater cores 10, 20 ofthe heating-use heat exchanger 2 are both provided with pluralities ofstacked flat tubes 11, 21, inlet side tank parts 12, 22 which arecommunicated with the pluralities of tubes 11, 21 at one end side in thelongitudinal direction and which become the cooling water inlet side,and exit side tank parts 13, 23 which are communicated with thepluralities of tubes 11, 21 at the other end side in the longitudinaldirection and which become the cooling water exit side.

The heating-use heat exchanger 2 is housed in the air-conditioning case51 along with a not shown blower which forms blown air directed to theinside of the passenger compartment and then is mounted in a vehicle.Specifically, as shown in FIG. 2, the heating-use heat exchanger 2 isheld in the air-conditioning case 51 in a slanted state so that thesecond heater core 20 is positioned at the downstream side in the airfrom the first heater core 10. “In the slanted state” means a state inwhich the air outflow/inflow surfaces of the heating-use heat exchanger2 are not parallel to both the vertical direction and horizontaldirection and in which the angle formed by the air outflow/inflowsurfaces and the vertical direction forms an acute angle. Further, theorientation of the air outflow/inflow surfaces of the heating-use heatexchanger 2 matches the longitudinal direction of the tubes 21 whenviewing the heating-use heat exchanger 2 from the side direction. In thepresent embodiment, the heating-use heat exchanger 2 is slanted so thatthe second heater core 20 is positioned above the first heater core 10.For this reason, directions of air flows which pass through the firstand the second heater cores 10, 20 are upward slanted directions.

Note that, in the present embodiment, as shown in FIG. 3, theheating-use heat exchanger 2 is mounted in the vehicle so that the topwall of the inlet side tank part 22 of the second heater core 20 becomesparallel to the horizontal direction when viewing the second heater core20 from the front.

The air-conditioning case 51, while not shown, is provided with a bypassair passage through which blown air flows bypassing the heating-use heatexchanger 2 and an air mix door which adjusts the mixing ratio of theair after passing through the bypass air passage and the air afterpassing through the heating-use heat exchanger 2. Note that, the airchannel through which air after passing through the heating-use heatexchanger 2 flows is connected at its bottom side to the foot vents andat its top side to the defroster vents and face vents.

The inlet side tank parts 12, 22 of the first and second heater cores10, 20 are comprised of a single inlet side tank 61 which is dividedinto two by a partition wall 62. They are provided with cooling waterinlets 10 a, 20 a. The cooling water inlets 10 a, 20 a are openingswhich are formed in the walls forming the inlet side tank parts 12, 22.They are end openings of the cooling water introduction path which facethe insides of the inlet side tank parts 12, 22 and which introducecooling water to the inlet side tank parts 12, 22. These cooling waterinlets 10 a, 20 a are arranged at one end side of the inlet side tankparts 12, 22 in the vehicle left-right direction (left-right directionof FIG. 3).

The exit side tank parts 13, 23 of the first and second heater cores 10,20 are comprised of a single exit side tank 63. This exit side tank 63is provided with a single cooling water exit 2 b. For this reason,inside of the exit side tank 63, the cooling water which flows into thefirst heater core 10 and the cooling water which flows into the secondheater core 20 merge. The merged cooling water flows out from a singlecooling water exit 2 b. Note that, the cooling water exit 2 b isarranged at one end side in the vehicle left-right direction the same asthe cooling water inlets 10 a, 20 a.

In this way, in the present embodiment, the exit side tank part of thefirst and second heater cores 10, 20 is made a common part and thecooling water exit 2 b of the heating-use heat exchanger 2 is made asingle exit, but it is also possible to provide each of the first andsecond heater cores 10, 20 with an exit side tank part and cooling waterexit. However, from the viewpoint of reducing the pipelines connectingthe heating-use heat exchanger 2 and the engine 30 and reducing thenumber of water pumps explained later, this embodiment is preferable.

The inlet side tank parts 12, 22 of the first and second heater cores10, 20 are positioned at the lower side, while the exit side tank parts13, 23 of the first and second heater cores 10, 20 are positioned at theupper side. For this reason, in both the first heater core 10 and thesecond heater core 20, the cooling water flows from the bottom towardthe top.

At both the first and second heater core 10, 20, a plurality of tubes11, 21 extend in one direction. They are stacked so as to be arranged inlines in a direction vertical to that one direction, that is, thevehicle left-right direction. The inlet side tank parts 12, 22 and exitside tank parts 13, 23 are shaped to extend elongated in the stackingdirections of the tubes 11, 21. Therefore, the “vehicle left-rightdirection” corresponds to the stacking directions of the tubes 11, 21and the longitudinal directions of the inlet side tank parts 12, 22.

The first and second heater cores 10, 20 are provided with corrugatedheat conduction fins 14, 24 which are joined to the outer surfaces ofthe tubes 11, 21. At the first and second heater cores 10, 20, due tothe stacked structures of the tubes 11, 21 and heat conduction fins 14,24, total pass type, that is, one-directional flow type first and secondheat exchange core parts 15, 25 are formed.

The first heater core 10 and the second heater core 20 are equal in sizein the left-right and top-bottom directions when viewed by the directionof air flow. Due to this, all of the air which passes through the firstheater core 10 passes through the second heater core 20.

Further, the first heater core 10 and the second heater core 20 differin thickness in the direction of air flow. Specifically, if comparingthe widths in the direction of air flow of the tubes 11, 21 and the heatconduction fins 14, 24, the first heater core 10 is longer than thesecond heater core 20. For this reason, the heat exchange area of theair and the cooling water becomes greater at the first heater core 10than at the second heater core 20.

Further, the channel sectional area of the tubes 11 of the first heatercore 10 is larger than the channel sectional area of the tubes 21 of thesecond heater core 20, and therefore the flow resistance in the firstheater core 10 is lower than the flow resistance in the second heatercore 20. For this reason, the first heater core 10 becomes greater inflow rate of cooling water flowing through the inside than the secondheater core 20.

Next, the operation of the vehicular air-conditioning system of thepresent embodiment 1 will be explained.

A not shown control device of the vehicular air-conditioning system 1controls the blower to obtain a blowing rate in accordance with thetarget vented air temperature TAO at the time of heating and controlsthe air mix door so as to obtain the desired position. The target ventedair temperature TAO is calculated in accordance with theair-conditioning heat load determined by the temperature setting andenvironmental conditions and is a target temperature of the air which isvented from the vents to the inside of the passenger compartment.

Due to this, in the first heater core 10, heat exchange with the coolingwater after cooling of the cylinder head 31 is used to heat the blownair. The cooling water after cooling of the cylinder head 31 positivelycools the cylinder head 31, so is lower in temperature than the minimumtemperature required for heating, but is larger in flow rate than thecooling water after cooling of the cylinder block 32 and has a largeheat content. Therefore, in the present embodiment, to take out as muchof the heat content of the cooling water after cooling of the cylinderhead 31 as possible, the cooling water flow rate at the inside of thefirst heater core 10 is increased compared with the second heater core20 and the heat conduction coefficient of the air and cooling water isincreased. For this reason, in the first heater core 10, it is possibleto supply the blown air with a large heat content from the large flowrate cooling water after cooling of the cylinder head 31. As a result,the temperature of the air after passing through the first heater core10 becomes a temperature close to the cooling water temperature beforeflowing into the first heater core 10 (inlet water temperature of firstheater core).

Further, in the second heater core 20, heat exchange with the coolingwater after cooling of the cylinder block 32 is used to heat the blownair after passing through the first heater core 10. The cooling waterafter cooling the cylinder block 32 is higher in temperature than thecooling water after cooling the cylinder head 31, so it is possible toraise the temperature of the blown air after passing through the secondheater core 20 to a temperature further higher than the blown air afterpassing through the first heater core 10.

In this regard, unlike in the present embodiment, as described in U.S.Pat. No. 5,337,704, only the cooling water which cools the cylinder head31 is used as a heat source for heating the air, so the air temperaturecannot be sufficiently raised and heating cannot be achieved. Further,when ending up mixing all of the cooling water after cooling of thecylinder head 31 which flows out from the engine and the cooling waterafter cooling of the cylinder block 32, the cooling water temperatureafter mixing becomes lower than the minimum temperature required forheating. For this reason, the efficiency of energy transfer from thecooling water to the air becomes lower, so even if using the coolingwater after mixing as the heat source to heat the air, it is notpossible to sufficiently raise the air temperature and heating cannot beachieved.

As opposed to this, in the present embodiment, the engine 30 is providedwith the first cooling water exit 31 b and the second cooling water exit32 b, the low temperature side cooling water after cooling the cylinderhead 31 is made to flow out from the first cooling water exit 31 b, andthe high temperature side cooling water after cooling the cylinder block32 is made to flow out from the second cooling water exit 32 b. Further,without allowing the two flows of cooling water to be mixed, the lowtemperature side cooling water which flows out from the first coolingwater exit 31 b is made to flow to the first heater core 10, and thehigh temperature side cooling water which flows out from the secondcooling water exit 32 b is made to flow to the second heater core 20.

In this way, in the present embodiment, in the second heater core 20,the high temperature side cooling water which flows out from the secondcooling water exit 32 b is used as a heat source to heat the air blowninto the passenger compartment, so when compared with the case of usingonly the low temperature side cooling water which flows out from thefirst cooling water exit 31 b as a heat source and the case of usingmixed water of the low temperature side cooling water and hightemperature side cooling water mixed together, it is possible to raisethe air temperature after heating at the second heater core 20.

Furthermore, in the present embodiment, the first heater core 10 usesthe low temperature side cooling water as a heat source to heat theblown air, then this heated air is heated at the second heater core 20using the high temperature side cooling water as a heat source, so it ispossible to effectively utilize the heat contents of both the lowtemperature side cooling water and the high temperature side coolingwater.

That is, according to the present embodiment, compared with the case ofusing a mixture of the cooling water as a whole which flows out fromboth the first and second cooling water exit parts 31 b, 32 b as a heatsource for heating the air blown into the passenger compartment by asingle heater core, it is possible to raise the efficiency of energytransfer from the cooling water to the air in the cooling water as awhole at the heater core. As a result, even when the blowing rate of theblower is large, it is possible to raise the air to a sufficiently hightemperature and possible to achieve heating.

Next, the main features of the vehicular air-conditioning system of thepresent embodiment 1 will be explained.

FIGS. 4 and 5 show the flows of cooling water in the second heater core20 in the present embodiment and Comparative Example 1, respectively.Comparative Example 1 sets the air-conditioning case 51 vertical so thatthe heating-use heat exchanger 2 has an air inflow surface parallel tothe vertical direction. Further, in Comparative Example 1, whenprojecting the cooling water inlet 20 a in the longitudinal direction ofthe inlet side tank part 22, the entire part of the cooling water inlet20 a of the inlet side tank part 22 is right under the inlet side end 21a of the tube 21. The high temperature cooling water is not stored inthe liquid storage part.

When the cooling water which flows into the second heater core 20 has alower flow velocity and lower flow rate than the cooling water whichflows into the first heater core 10, in Comparative Example 1 shown inFIG. 5, the phenomenon ends up arising that most of the high temperaturecooling water which flows into the inlet side tank part 22 flows throughthe tubes close to the cooling water inlet and it is difficult for thecooling water to flow up to the tubes far from the cooling water inlet.

As opposed to this, in the present embodiment, as shown in FIG. 2, thesecond heater core 20 is made to slant, so in the region of the inletside tank part 22 which is above the inlet side ends 21 a of the tubes21, a liquid storage part 71 is formed in which the high temperaturecooling water is stored across the entire region of the plurality oftube 21 in the stacked direction. This liquid storage part 71 is formedinto a corner part which is positioned at the highest position in thecorner part of the inlet side tank part 22.

For this reason, as shown in FIG. 4, the cooling water which flowed tothe inlet side tank part 22 and which is higher in temperature than thecooling water inside of the exit side tank part is stored in the liquidstorage part 71 due to the buoyancy effect, then flows from this liquidstorage part 71 to the plurality of tubes.

In particular, in the present embodiment, as shown in FIG. 2, whenprojecting the cooling water inlet 20 a in the longitudinal direction ofthe inlet side tank part 22 (direction vertical to paper surface in FIG.2), part of the cooling water inlet 20 a is positioned at the outsidefrom a tube inside extension line (imaginary line) 81 drawn parallel inthe gravity direction from the tube inside walls 21 b of the tubes 21 atthe inlet side end 21 a.

Here, when projecting the cooling water inlet 20 a in the longitudinaldirection of the inlet side tank part 22, if all of the cooling waterinlet 20 a of the inlet side tank part 22 is positioned right under theinlets of the tubes 21 in the gravity direction, the high temperaturecooling water which flows into the inlet side tank part 22 will rise dueto buoyancy, so when high temperature cooling water flows in from thecooling water inlet 20 a to the inlet side tank part 22, the hightemperature cooling water will end up flowing in to the tubes 21positioned above the inflowing cooling water.

As opposed to this, in the present embodiment, part of the cooling waterinlet 20 a is positioned other than right below the inlets of the tubes21, so part of the high temperature cooling water which flows in fromthe cooling water inlet 20 a can be reliably guided to the liquidstorage part 71.

Therefore, according to the present embodiment, compared withComparative Example 1, it is possible to reduce the temperaturedifference in the vehicle left-right direction of the cooling waterwhich flows through the heat exchange core part 25. Accordingly,according to the present embodiment, it is possible to reduce thetemperature difference in the vehicle left-right direction caused by theair-conditioned air after passing through the heating-use heat exchanger2.

As a result, when the air-conditioned air after passing through theheating-use heat exchanger 2 is branched to one side and the other sidein the vehicle left-right direction and air-conditioned air is ventedfrom the driver side vents and passenger side vents, the temperaturedifference of the vented air at the driver's side and passenger side inthe passenger compartment is reduced.

Further, according to the present embodiment, compared with ComparativeExample 1, the substantial heat exchange area at the heat exchange corepart 25 increases, so the heat content which can be taken from thecooling water at the heat exchange core part 25 is improved and the heatexchange performance is improved.

Second Embodiment

FIG. 6 is a cross-sectional view of the heating-use heat exchanger 2 inthe present embodiment. FIG. 6 is a view seen along the same directionas FIG. 2.

In the present embodiment as well, as shown in FIG. 6, the second heatercore 20 is slanted, so a liquid storage part 71 is formed in the regionof the inlet side tank part 22 above the inlet side ends 21 a of thetubes 21.

Furthermore, in the present embodiment, the positional relationshipbetween the cooling water inlet 20 a and the tubes 21 at the inlet sidetank part 22 of the second heater core 20 is as follows: That is, asshown in FIG. 6, when projecting the cooling water inlet 20 a at thelongitudinal direction of the inlet side tank part 22, part of thecooling water inlet 20 a (not hatched region in FIG. 6) is positionedbelow the inlet side ends of the tubes 21 (bottom end face) 21 a.

Further, the majority of the cooling water inlet 20 a (hatched region inFIG. 6) is positioned outside from between two imaginary lines 81, 82drawn from the tube inside walls 21 b of the tubes 21 at the inlet sideends 21 a parallel in the gravity direction. Here, “the majority of thecooling water inlet 20 a” means a part accounting for 50% or more of thearea of the cooling water inlet 20 a. Further, the position at the lowerside from the inlets of the tubes 21 between the two imaginary lines 81,82 is a position right below the inlets of the tubes 21.

In this way, in the present embodiment, 50% or more of the total area ofthe cooling water inlet 20 a, that is, the majority, sticks out to theoutside from the region between the two imaginary lines 81, 82, so it ispossible to guide at least half of the cooling water which flows in fromthe cooling water inlet 20 a to the liquid storage part 71.

Third Embodiment

FIG. 7 is a cross-sectional view of a heating-use heat exchanger 2 inthe present embodiment. FIG. 7 is a view seen along the same directionas FIG. 2.

In the present embodiment as well, as shown in FIG. 7, the second heatercore 20 is slanted. In the same way as the first and second embodiments,a not shown liquid storage part is formed in the inlet side tank part 22in the region above the inlet side ends 21 a of the tubes 21.

Further, the positional relationship between the cooling water inlet 20a and the tubes 21 at the inlet side tank part 22 of the second heatercore 20 is as follows:

That is, as shown in FIG. 7, when projecting the cooling water inlet 20a in the longitudinal direction of the inlet side tank part 22, part ofthe cooling water inlet 20 a (non-hatched region in FIG. 7) ispositioned right under the inlet side ends (bottom end faces) 21 a ofthe tubes 21. The rest of the cooling water inlet 20 a (hatched part inFIG. 7) is positioned other than right below the tubes 21. Specifically,part of the cooling water inlet 20 a (hatched region in FIG. 7 withdirection of hatching from top left to bottom right) is positionedoutside from between two imaginary lines 81, 82 drawn from the tubeinside walls 21 b of the tubes 21 at the inlet side end 21 a in parallelin the gravity direction. Furthermore, part of the cooling water inlet20 a (hatched region in FIG. 7 with direction of hatching from top rightto bottom left) is positioned at the upper side of the imaginary line 83extending in line with the inlet side ends 21 a of the tubes 21, whilepart of the cooling water inlet 20 a overlaps the tubes 21 in positionalrelationship. Note that, “the inlet side end 21 a through which theimaginary line 83 passes” is the inlet side end faces of the tubes 21when projecting the cooling water inlet 20 a in the longitudinaldirection of the inlet side tank part 22. Further, “positioned at theupper side of the imaginary line 83” means positioned at the other endside of the tubes 21 in the longitudinal direction than the imaginaryline 83.

Incidentally, when, like with the first heater core 10, the inflowingcooling water is large in flow rate, if positioning part of the coolingwater inlet at the upper side from the inlet side end faces of the tubesand making part of the cooling water inlet overlap the tubes inpositional relationship, the problem arises of the pressure lossincreasing when the cooling water flows through the inlet side tank part22, so this positional relationship cannot be employed. As opposed tothis, when, like with the second heater core 20, the inflowing coolingwater is small in flow rate, the problem of increase of the pressureloss does not arise, so a positional relationship where part of thecooling water inlet 20 a overlaps the tubes 21 can be employed.

In this way, by positioning part of the cooling water inlet 20 a at theoutside from between two imaginary lines 81, 82 parallel in the gravitydirection and, further, positioning it at the upper side from the inletside end face of the tubes 21 as well, part of the high temperaturecooling water which flows in from the cooling water inlet 20 a can bereliably guided to the liquid storage part 71. As a result, according tothe present embodiment, it is possible to reduce the temperaturedifference in the vehicle left-right direction occurring in theair-conditioned air after passing through the heating-use heat exchanger2.

Here, the relationship between the ratio of the area of the part of thecooling water inlet 20 a positioned other than right below the inlets ofthe tubes 21 with respect to the total area (below simply referred to asthe “area ratio”) and the effect of reduction of the temperaturedifference in the vehicle left-right direction occurring in theair-conditioned air after passing through the heating-use heat exchanger2 will be explained.

FIG. 8 is a side view of the heating-use heat exchanger 2 for explainingthe slant angle θ1 of the second heater core 20. FIG. 9 shows theresults of evaluation showing the relationship between the temperaturedifference of the left-right vented air from the heating-use heatexchanger 2 and the slant angle θ1 shown in FIG. 8. FIG. 10 shows theresults of evaluation when changing the abscissa in FIG. 9 from theslant angle θ1 to the area ratio. The slant angle θ1, as shown in FIG.8, is the angle formed by the longitudinal direction of the tubes 21 andthe vertical direction when viewing the heating-use heat exchanger 2from the side. The “temperature difference of the left-right vented airfrom the heating-use heat exchanger 2” is the difference (absolutevalue) between the average temperature of the vented air from one halfof the heating-use heat exchanger in the left-right direction and theaverage temperature of the vented air from the other half.

In the heating-use heat exchanger 2 shown in FIG. 8, in the same way asthe heating-use heat exchanger shown in FIG. 3, the cooling water inlet20 a is provided at the end at one side in the left-right direction.Further, in the heating-use heat exchanger 2 shown in FIG. 8, in thedirection of air flow, the diameter of the cooling water inlet 20 a issubstantially equal to the inside diameter of the tube 21, the center ofthe cooling water inlet 20 a and the center of the tubes 21 are the sameposition, and part of the cooling water inlet 20 a is positioned at theupper side from the inlet side end face of the tubes 21.

In such a heating-use heat exchanger 2, if the slant angle θ1 changes,the area ratio also changes. Specifically, the slant angle θ1 in FIGS. 9of 0, 10, 20, 50, and 90 degrees corresponds to an area ratio in FIG. 10of 8, 25, 35, 65, and 100%. When the slant angle θ1 is 0 degree, thearea of the part of the cooling water inlet 20 a positioned outside frombetween the two imaginary lines 81, 82 parallel in the gravity direction(see hatched region of FIG. 7 with direction of hatching from top leftto bottom right) becomes the minimum. If increasing the slant angle θ1,as shown in FIG. 7, the cooling water inlet 20 a increases in area ofthe part positioned outside from between the imaginary lines 81, 82parallel in the gravity direction. When the slant angle θ1 is 90degrees, the inlet side end faces of the tubes 21 become parallel to thevertical direction, so the imaginary lines 81, 82 overlap into one.There is no region of the tubes 21 right below the inlet, so the arearatio becomes 100%. Note that, the area of the part where the coolingwater inlet 20 a overlaps the tubes 21 is constant regardless of theslant angle θ.

As shown in FIGS. 9 and 10, the temperature difference of the left-rightvented air from the heating-use heat exchanger 2 tends to become smalleras the slant angle θ1 increases, that is, the area ratio increases. Inparticular, the temperature difference of the left-right vented air whenthe slant angle θ1 is 20 degrees or more, that is, the area ratio is 35%or more, becomes close to the temperature difference when the slantangle θ1 is 90 degrees, that is, the area ratio is 100%. From this, toparticularly reduce the temperature difference of the left-right ventedair from the heating-use heat exchanger 2, it can be said preferablethat the area ratio be made 35% or more.

Further, in the present embodiment, the part of the cooling water inlet20 a overlaps with the tube 21 in the positional relationship. As willbe understood from a comparison of the inlet side tank part 22 in FIG. 6explained in the second embodiment, the dimension of the inlet side tankpart 22 in the tube longitudinal direction can be reduced.

Note that, in the present embodiment, to enable part of the coolingwater inlet 20 a (hatched region in FIG. 7) to be positioned other thanright under the tubes 21, part of the cooling water inlet 20 a ispositioned outside from between two imaginary lines 81, 82 parallel inthe gravity direction and is positioned at the upper side from theimaginary line 83 extending in line with the inlet side ends of thetubes 21. That is, two configurations are employed, but it is alsopossible to employ only one. In these cases as well, in the same way asthe present embodiment, the area ratio is preferably made 35% or more.

Fourth Embodiment

FIG. 11 is a cross-sectional view of the heating-use heat exchanger 2 inthe present embodiment. FIG. 11 is a view seen from the same directionas FIG. 2.

In the present embodiment, unlike the first to third embodiments, thevehicle mounted posture of the heating-use heat exchanger 2 is made aposture where the air outflow/inflow surfaces are parallel to thevertical direction. That is, the heating-use heat exchanger 2 is held inthe air-conditioning case in an orientation with longitudinal directionsof the tubes 11, 21 parallel to the vertical direction.

In the second heater core 20, part 91 of the wall forming the inlet sidetank part 22 bulges outward from the other parts. Due to this bulgedpart 91, a liquid storage part 72 where the high temperature coolingwater is stored is formed. Note that, the liquid storage part 72 of thepresent embodiment is also a region of the inlet side tank part 22 abovethe inlet side ends 21 a of the tubes 21.

Specifically, the inlet side tank part 22, while not shown, is comprisedof a core plate in which the tubes 21 are inserted and a tank bodyjoined together. Part 91 of the core plate of the wall of the upper sideforming the inlet side tank part 22 bulges to the outside.

Further, in the present embodiment as well, the positional relationshipbetween the cooling water inlet 20 a and the tubes 21 in the inlet sidetank part 22 is as follows:

That is, as shown in FIG. 11, part of the cooling water inlet 20 a(non-hatched region in FIG. 11) is positioned below the inlet side ends(bottom end faces) 21 a of the tubes 21. Further, part of the coolingwater inlet 20 a (hatched region in FIG. 11) is positioned outside frombetween two imaginary lines 81, 82 drawn from the tube inside walls 21 bat the inlet side ends 21 a of the tubes 21 in parallel in the gravitydirection.

Therefore, in the present embodiment as well, part of the cooling waterinlet 20 a is positioned other than right under the inlets of the tubes21, so the high temperature cooling water flowing in from the coolingwater inlet 20 a can be reliably guided to the liquid storage part 72.Further, it is possible to run high temperature cooling water from thisliquid storage part 72 to the plurality of tubes 21, so it is possibleto reduce the temperature difference in the vehicle left-right directionof the cooling water flowing through the heat exchange core part andpossible to reduce the temperature difference in the vehicle left-rightdirection occurring in the air-conditioned air after passing through theheating-use heat exchanger 2. Note that, in the present embodiment aswell, in the same way as the third embodiment, the area ratio ispreferably made 35% or more.

Fifth Embodiment

FIG. 12 shows a cross-sectional view of the heating-use heat exchanger 2in the present embodiment. FIG. 12 is a view seen from the samedirection as FIG. 2.

The present embodiment changes the orientation of the heating-use heatexchanger 2 explained in the third embodiment, in the same way as thefourth embodiment, to an orientation in which the longitudinal directionof the tubes 11, 21 is parallel to the vertical direction. However, inthe present embodiment, the inlet side tank part 22 of the second heatercore 20 is not provided with the bulged part 91 in FIG. 11 explained inthe fourth embodiment.

Specifically, as shown in FIG. 12, in the present embodiment as well, aliquid storage part 73 is formed in the inlet side tank part 22 in theregion of above the inlet side ends 21 a of the tubes 21.

Further, when projecting the cooling water inlet 20 a in thelongitudinal direction of the inlet side tank part 22, part of thecooling water inlet 20 a (non-hatched region in FIG. 12) is positionedbelow the inlet side ends (bottom end faces) 21 a of the tubes 21.

Further, part of the cooling water inlet 20 a (hatched region in FIG. 12with hatching oriented from top left to bottom right) is positionedoutside from between two imaginary lines 81, 82 drawn from the tubeinside walls 21 b of the tubes 21 at the inlet side end 21 a in parallelin the gravity direction. Furthermore, part of the cooling water inlet20 a (hatched region in FIG. 12 with hatching oriented from top right tobottom left) is positioned at the upper side from an imaginary line 83extending in line with the inlet side end faces of the tubes 21.

Therefore, in the present embodiment as well, an effect similar to thethird embodiment is exhibited. Note that, in the present embodiment aswell, in the same way as the third embodiment, the area ratio ispreferably made 35% or more.

Further, from the viewpoint of securing the volume of the liquid storagepart 73, like in the later explained sixth embodiment, it is preferableto lengthen the insertion length of the tubes 21 which are inserted intothe inlet side tank part 22 of the second heater core 20 compared with ageneral heat exchanger.

Sixth Embodiment

FIG. 13 is a cross-sectional view of a heating-use heat exchanger 2 inthe present embodiment. FIG. 13 is a view seen from the same directionas FIG. 2.

As shown in FIG. 13, the heating-use heat exchanger 2 of the presentembodiment, like the fourth and fifth embodiments, is held inside theair-conditioning case with the longitudinal directions of the tubes 11,21 oriented parallel to the vertical direction.

Further, the insertion length 84 of the tubes 21 inserted into the inletside tank part 22 of the second heater core 20 is longer than theinsertion length 85 of the tubes 11 inserted into the inlet side tankpart 12 of the first heater core 10. The “insertion lengths 84, 85” arethe lengths from the inside walls of the inlet side tank parts 22, 12 tothe inlet side ends 21 a, 11 a of the tubes 21, 11. Due to this, thevolume of the liquid storage part 74 which is formed in the region ofthe inlet side tank part 22 above the inlet side ends 21 a of the tubes21 is increased.

In the present embodiment, in the positional relationship between thecooling water inlet 20 a and the tubes 21 at the inlet side tank part 22of the second heater core 20, the majority of the cooling water inlet 20a (hatched region in FIG. 13) is positioned at the upper side from theimaginary line 83 extending in line with the inlet side ends (inlet sideend faces) 21 a of the tubes drawn parallel in the horizontal direction.Here, the majority of the cooling water inlet 20 a, like the explanationin the third embodiment, preferably has an area ratio of 35% or more.

Note that, like in the present embodiment, when the insertion length 84of the tubes 21 which are inserted at the inlet side tank part 22 of thesecond heater core 20 is long, it is most preferable that the position20 a 1 of the bottom end of the cooling water inlet 20 a be the sameposition as the inlet side ends 21 a of the tubes 21 or a position abovethe same. That is, it is most preferred that 100% of the area of thecooling water inlet 20 a overlap the tubes 21 in positionalrelationship. Due to this, it is possible to guide all of the hightemperature cooling water which flows in from the cooling water inlet 20a to the liquid storage part 74.

Seventh Embodiment

FIG. 14 is a front view of a heating-use heat exchanger in the presentembodiment. The present embodiment changes the vehicle-mounted postureof the heating-use heat exchanger 2 shown in FIG. 12 explained in thefifth embodiment so that the air outflow/inflow surfaces are parallel tothe vertical direction and further so that the inlet side tank part 22is slanted upward in the gravity direction from the cooling water inlet20 a down to the deep parts. The rest of the configuration is similar tothat of the fifth embodiment.

Specifically, as shown in FIG. 14, the inlet side tank part 22 of thesecond heater core 20 has the cooling water inlet 20 a at one side endof the inlet side tank part 22 in the longitudinal direction (left-rightdirection). Cooling water flows from one side end of the inlet side tankpart 22 in the longitudinal direction. Further, when viewing the secondheater core 20 from the front side, the second heater core 20 is slantedin state so that the top wall of the inlet side tank part 22 ispositioned with one end side of the inlet side tank part 22 in thelongitudinal direction positioned upward in the gravity direction thanthe other end side in the longitudinal direction. At this time, thesecond heater core 20 has an angle formed by the top wall of the inletside tank part 22 of the second heater core 20 and the horizontaldirection as the slant angle θ2 and has a predetermined slant angle θ2.

Here, the “top wall” of the inlet side tank part 22 is the core platewhen the inlet side tank part 22 is comprised of a core plate in whichthe tubes 21 are inserted and a tank body forming the tank part.Further, the predetermined slant angle θ2 may be made the same 1 to 1.5degrees of the standard mold extraction gradient for mold extractionprovided at the holding part of a heating-use heat exchanger of anair-conditioning case at the time of molding an air-conditioning casefrom plastic, but a size over this, for example, 3 degrees or more, ispreferable. The second heater core 20 is mounted in the vehicle whileheld inside the air-conditioning case 51 in this slanted state.

In this way, by making the top wall of the inlet side tank part 22slanted so that the deep part is positioned at the top from the coolingwater inlet 20 a, it is possible to make the high temperature coolingwater flowing through the liquid storage part travel along the top wallto enable it to be more easily guided to the deep side of the inlet sidetank part 22 far from the cooling water inlet 20 a compared with thecase where the top wall of the inlet side tank part 22 is horizontal. Asa result, according to the present embodiment, compared with the fifthembodiment where the top wall of the inlet side tank part 22 ishorizontal, it is possible to reduce the temperature difference in thevehicle left-right direction occurring in the air-conditioned air afterpassing through the heating-use heat exchanger 2.

FIG. 15 shows the results of evaluation of the relationship of the slantangle θ2 and the left-right vented air temperature difference. As willbe understood from FIG. 15, in the range of the slant angle θ2 of 0 to12 degrees, as the slant angle θ2 becomes larger, the left-right ventedair temperature difference tends to fall, but in the range of the slantangle θ2 exceeding 12 degrees, as the slant angle θ2 becomes larger, theleft-right vented air temperature difference tends to increase.Therefore, as the upper limit of the slant angle θ2, 19.5 degrees, thesame as the left-right vented air temperature difference (absolutevalue) when the slant angle θ2 is 3 degrees, is preferable.

Note that, in the present embodiment, the heating-use heat exchanger 2as a whole is slanted to make the angle formed by the top wall of theinlet side tank part 22 of the second heater core 20 and the horizontaldirection a predetermined slant angle θ2, but instead of slanting theheating-use heat exchanger 2 as a whole, the shape of the inlet sidetank part 22 of the second heater core 20 may be made a shape with thetop wall of the inlet side tank part 22 slanted.

Further, the present embodiment is not limited to the fifth embodimentand can also be applied to the fourth and sixth embodiments where theair outflow/inflow surfaces are made parallel to the vertical directionand to the first to third embodiments where the air outflow/inflowsurfaces are made slanted.

Eighth Embodiment

In the above embodiments, a liquid storage part is formed for storinghigh temperature cooling water at the inside of the inlet side tank part22, but the present embodiment raises the flow velocity of the coolingwater at the cooling water inlet side of the inlet side tank part 22.

FIG. 16 is a front view of the second heater core 20 in the presentembodiment. As shown in FIG. 16, in the present embodiment, the coolingwater inlet side at the inside of the inlet side tank part 22 isprovided with, as a flow velocity raising means for raising the flowvelocity of the cooling water flowing into the inlet side tank part 22,a plate-shaped member 92 which has a communication hole 91 with asmaller channel sectional area than the inlet side tank part 22.

Regarding the dimensions of the communication hole 91, for example, whenthe diameter of the inside of the inlet side tank part 22 is 16 mm, thediameter of the communication hole 91 is made 5 mm or less. In this way,the diameter of the communication hole 91 is made about ⅓ or less of thediameter of the inlet side tank part 22.

Due to this, according to the present embodiment, it is possible toraise the flow velocity of the cooling water after passing through thecommunication hole 91 compared with the flow velocity of the coolingwater before passing through the communication hole 91.

As explained in the first embodiment, when the cooling water which flowsinto the second heater core 20 has a small flow rate, if the flowvelocity of the cooling water which flows through the inlet side tankpart 22 is low, the phenomenon ends up arising that it becomes hard forthe cooling water to flow up to the tubes far from the cooling waterinlet.

As opposed to this, according to the present embodiment, it is possibleto raise the flow velocity of the cooling water which flows into theinlet side tank part 22, so compared with when not providing means forraising the flow velocity of the cooling water, it is possible to runcooling water deep into the inlet side tank part 22.

Accordingly, in the present embodiment as well, it is possible to reducethe temperature difference in the vehicle left-right direction of thecooling water flowing through the heat exchange core part 25 andpossible to reduce the temperature difference in the vehicle left-rightdirection occurring in the air-conditioned air after passing through theheating-use heat exchanger 2.

Note that, in the present embodiment, the liquid storage parts explainedin the first to the seventh embodiments are not formed, but it is alsopossible to form liquid storage parts in the same way as the first tothe seventh embodiments. That is, the embodiment may be combined withthe first to seventh embodiments. By combination, a higher advantageouseffect is obtained.

Ninth Embodiment

FIG. 17 is a cross-sectional view of the heating-use heat exchanger 2 inthe present embodiment. FIG. 17 is a view seen from the same directionas FIG. 2. In the present embodiment, compared with the heating-use heatexchanger 2 shown in FIG. 12 explained in the fifth embodiment, theopening area of the cooling water inlet 20 a of the second heater core20 and the channel sectional area of the not shown cooling waterintroduction path are made smaller than those of the first heater core10 so as to increase the flow velocity of the cooling water flowingthrough the inlet side tank part 22 of the second heater core 20. Here,the “cooling water introduction path” means the pipeline communicatedwith the cooling water inlet 20 a for guiding cooling water to the inletside tank part 22.

For this reason, according to the present embodiment, compared with thecase where the opening area of the cooling water inlet 20 a of thesecond heater core 20 and channel sectional area of the not shown thecooling water introduction path are equal to those of the first heatercore 10, it is possible to run cooling water deep into the inlet sidetank part 22.

Further, in the present embodiment, the channel sectional area of theinlet side tank part 22 of the second heater core 20 becomes smallerthan the channel sectional area of the inlet side tank part 12 of thefirst heater core 10. Due to this as well, compared with the case wherethe channel sectional area of the inlet side tank part 22 of the secondheater core 20 is equal to the channel sectional area of the inlet sidetank part 12 of the first heater core 10, it is possible to raise theflow velocity of the cooling water flowing through the inlet side tankpart 22 of the second heater core 20 and possible to run cooling waterdeep into the inlet side tank part 22.

In the present embodiment, the flow velocity of the cooling water whichflows through the inlet side tank part 22 of the second heater core 20is preferably raised so as to become equal to or more than the flowvelocity of the cooling water which flows through the inlet side tankpart 12 of the first heater core 10.

Note that, in the present embodiment, both the opening area of thecooling water inlet 20 a of the second heater core 20 and the channelsectional area of the not shown cooling water introduction path and thechannel sectional area of the inlet side tank part 22 of the secondheater core 20 are made smaller, but it is also possible to use just oneto raise the flow velocity of the cooling water flowing through theinlet side tank part 22 of the second heater core 20. Further, in thisway, the configuration for raising the flow velocity of the coolingwater flowing through the inlet side tank part 22 of the second heatercore 20 is not limited to the fifth embodiment. This may also be appliedto the heating-use heat exchanger which are explained in the otherembodiments.

In the present embodiment as well, part of the cooling water inlet 20 a(hatched region in FIG. 17) is positioned outside from between twoimaginary lines 81, 82 drawn from the tube inside walls 21 b at theinlet side end 21 a of the tubes 21 in parallel in the gravitydirection. For this reason, part of the high temperature cooling waterwhich flows from the cooling water inlet 20 a can be guided to theliquid storage part 73.

Note that, in the present embodiment, by raising flow velocity of thecooling water which flows through the inlet side tank part 22 of thesecond heater core 20, it is possible to run cooling water deep into theinlet side tank part 22, so all of the cooling water inlet 20 a may bepositioned right under the inlet of the tubes 21.

Further, in the present embodiment, the tank parts of the first heatercore 10 and the second heater core 20 are made integral and the tubes11, 21 of the first heater core 10 and the second heater core 20 aremade integral to make the first heater core 10 and the second heatercore 20. The tubes 11, 21 of the first heater core 10 and the secondheater core 20 are connected, but the channels at the inside of thetubes 11, 21 are separately formed at the first heater core 10 and thesecond heater core 20. At this time, the fins of the first heater core10 and the second heater core 20 may be made separate or joined.

10th Embodiment

FIG. 18A is a side view of a heating-use heat exchanger 2 in the presentembodiment, while FIG. 18B is a front view of a second heater core 20 inFIG. 18A.

The present embodiment is the same as the first embodiment in thestructure of the heating-use heat exchanger 2, but differs from thefirst embodiment in the up-down relationship of the heating-use heatexchanger 2. That is, the inlet side tank parts 12, 22 of the first andsecond heater cores 10, 20 are positioned at the upper side, while theexit side tank parts 13, 23 of the first and second heater cores 10, 20are positioned at the lower side. Further, the heating-use heatexchanger 2 is held in the air-conditioning case with the longitudinaldirection of the tubes 11, 21 oriented parallel to the verticaldirection.

For this reason, in the present embodiment, when cooling water flows tothe inlet side tank part 22 of the second heater core 20, as shown inFIG. 18B, cooling water higher in temperature than the cooling waterinside of the exit side tank part 23 is, due to the effect of buoyancy,stored in the upper region 75 inside of the inlet side tank part 22 overthe entire stacked direction of the plurality of tubes 21, then flowsfrom this upper region 75 to the plurality of tubes. Further, the hightemperature cooling water flows through the plurality of tubes 21 fromthe top toward the bottom. In this way, in the present embodiment, theupper region 75 inside the inlet side tank part 22 becomes the liquidstorage part.

Accordingly, according to the present embodiment, it is possible toreduce the temperature difference in the vehicle left-right direction ofthe cooling water flowing through the heat exchange core part 25 andpossible to reduce the temperature difference in the vehicle left-rightdirection occurring in the air-conditioned air after passing through theheating-use heat exchanger 2.

11th Embodiment

FIG. 19 is a side view of the heating-use heat exchanger 2 in thepresent embodiment. The present embodiment changes the up-downrelationship of the first heater core 10 in the heating-use heatexchanger 2 shown in FIGS. 18A and 18B explained in the 10th embodiment.Specifically, as shown in FIG. 19, the first heater core 10 and thesecond heater core 20 have integral tank parts at the inlet side and theexit side whereby the two are formed integral in structure.

The inside of the upper side tank part 61 which is positioned at theupper side of the heating-use heat exchanger 2 is divided by thepartition wall 62 into the exit side tank part 13 of the first heatercore 10 and the inlet side tank part 22 of the second heater core 20.

Similarly, the inside of the bottom side tank part 63 positioned at thelower side of the heating-use heat exchanger 2 is divided by a partitionwall 64 to the inlet side tank part 12 of the first heater core 10 andthe exit side tank part 23 of the second heater core 20.

In the first heater core 10, the cooling water which flows in from thecooling water inlet 10 a which is provided at the inlet side tank part12 positioned at the lower side flows through the tube 11 from thebottom to the top, while flows out from the cooling water exit 10 bwhich is provided at the exit side tank part 13 positioned at the upperside.

On the other hand, in the second heater core 20, the cooling water whichflowed in from the cooling water inlet 20 a provided at the upper sideflows through the tubes 21 from the top toward the bottom and flows outfrom the cooling water exit 20 b provided at the exit side tank part 23provided at the lower side.

In the present embodiment as well, the inlet side tank part 22 of thesecond heater core 20 is positioned at the upper side, so advantageouseffects similar to the eighth embodiment are obtained.

Furthermore, according to the present embodiment, the direction of flowof the cooling water inside of the first heater core 10 is opposite tothe direction of flow of the cooling water inside of the second heatercore 20, so it is possible to reduce the up-down temperaturedistribution after passing through the heating-use heat exchanger 2,that is, the temperature difference between the upper side and the lowerside.

Other Embodiments

(1) In the above embodiments, the cooling water inlet 20 a provided atthe inlet side tank part 22 of the second heater core 20 is an openingformed in the wall forming the inlet side tank part 22, but it is alsopossible to insert a pipe into this opening to obtain a state with apipe sticking out from the inside wall of the inlet side tank part 22 tothe inside of the inlet side tank part 22. In this case, the front endpart of the pipe sticking out inside of the inlet side tank part 22 isan end opening of the cooling water introduction path which faces theinside of the inlet side tank part 22 and introduces cooling water tothe inlet side tank part 22.

(2) In the above first to seventh and ninth to 11th embodiments, thecooling water inlet 20 a of the second heater core 20 is arranged at oneend side of the inlet side tank part 22 in the vehicle left-rightdirection, but it need not be arranged at only one end side. It may bearranged at the two end sides or may be arranged at the center. Evenwith such an arrangement, according to the present invention, hightemperature cooling water can be run into the tubes 21 positioned farfrom the cooling water inlet 20 a.

(3) In the above embodiments, the first heater core 10 and the secondheater core 20 are integrally formed, but the first heater core 10 andthe second heater core 20 may also be separate members.

Furthermore, in the above embodiments, the orientation of the flow ofcooling water inside the first heater core 10 is the same down-to-uporientation as the second heater core 20, but may also be an up-to-downorientation opposite to the second heater core 20.

(4) In the above embodiments, the cooling water flowing out from thefirst cooling water exit 31 b of the engine 30 is only the cooling watercooling the cylinder head 31, but also may be cooling water comprised ofthe cooling water cooling the cylinder head 31 into which part of thecooling water cooling the cylinder block 32 is mixed. In short, it issufficient that mainly cooling water cooling the cylinder head 31 flowout from the first cooling water exit 31 b of the engine 30.

Similarly, the cooling water flowing out from the second cooling waterexit 32 b of the engine 30 is only the cooling water cooling thecylinder block 32, but may also be cooling water comprised of thecooling water cooling the cylinder block 32 into which part of thecooling water cooling the cylinder head 31 is mixed. In short, thecooling water cooling the cylinder block 32 mainly flows out from thesecond cooling water exit 32 b of the engine 30. It is sufficient thatthe cooling water which flows out from the second cooling water exit 32b be higher in temperature than the cooling water flowing out from thefirst cooling water exit 31 b.

However, the cooling water flowing out from the second cooling waterexit 32 b of the engine 30 is made a higher temperature than the case ofthe entire cooling water after cooling the cylinder head 31 and coolingwater after cooling the cylinder block 32 mixed together. Due to this,compared with the case of mixing the entire amounts of the two flows ofcooling water, it is possible to make higher temperature cooling waterflow out from the engine 30.

(5) In the above embodiments, the cooling water which flows into thesecond heater core 20 is just the cooling water flowing out from thesecond cooling water exit 32 b of the engine 30, but part of the coolingwater flowing out from the first cooling water exit 31 b may also bemixed in.

In short, it is sufficient that mainly cooling water flowing out fromthe second cooling water exit 32 b and higher in temperature than thecooling water flowing into the first heater core 10 flow into the secondheater core 20. However, the cooling water which flows into the secondheater core 20 becomes higher in temperature than the averagetemperature when mixing the entire amounts of the cooling water whichflows out from the second cooling water exit 32 b and the cooling waterwhich flows out from the first cooling water exit 31 b. Due to this,compared with when mixing the entire amounts of the two flows of coolingwater, the air temperature after heating at the second heater core 20can be raised.

(6) In the above embodiments, the first heater core 10 uses the coolingwater after cooling the cylinder head as the heat source, while thesecond heater core 20 uses the cooling water after cooling the cylinderblock as the heat source, but the first heater core 10 and the secondheater core 20 may also use other liquids as the heat sources. When thefirst heater core 10 uses a first liquid as a heat source and the secondheater core 20 uses a second liquid with a higher temperature andsmaller flow rate than the first liquid as a heat source, the presentinvention can be applied.

For example, in a vehicular air-conditioning system which is mounted ina hybrid vehicle, it is possible to use a cooling solution of aninverter or other electric device as the first liquid and use a coolingsolution of the engine as the second liquid. Further, for example, in avehicular air-conditioning system which is mounted in an electricvehicle, it is possible to use a cooling solution of an inverter orother electric device as the first liquid and use a high temperatureliquid heated by the electric heater or other heating means as thesecond liquid. In this way, the vehicular air-conditioning system of thepresent invention can be applied to vehicles other than hybrid vehiclesas well.

(7) The above embodiments may be combined in a workable range.

While the invention has been described by reference to specificembodiments chosen for purposes of illustration, it should be apparentthat numerous modifications could be made thereto by those skilled inthe art without departing from the basic concept and scope of theinvention.

1. A vehicular air-conditioning system comprising a heating-use heatexchanger which uses a first liquid and a second liquid with a highertemperature and smaller flow rate than said first liquid as heat sourcesto heat air blown into a passenger compartment, wherein said heating-useheat exchanger comprises a first heat exchange part which exchanges heatbetween said first liquid and said blown air, and a second heat exchangepart which exchanges heat between said second liquid and said blown airwhich was heated by said first heat exchange part, said second heatexchange part comprises a plurality of tubes stacked together, an inletside tank part which is connected to first end sides of said pluralityof tubes in the longitudinal direction and which forms a liquid inletside, and an exit side tank part which is connected to the other endsides of the plurality of tubes in the longitudinal direction and whichforms a liquid exit side, said second heat exchange part is held in anair-conditioning case so that said inlet side tank part is positioned ata lower side in a gravity direction and so that said exit side tank partis positioned at an upper side in a gravity direction, and said secondheat exchange part is configured to store the second liquid which flowsinto said inlet side tank part and which is higher in temperature thanthe liquid inside said exit side tank part in liquid storage parts insaid inlet side tank part across the entire stacked direction of saidplurality of tubes, then release it to said plurality of tubes.
 2. Avehicular air-conditioning system as set forth in claim 1, wherein saidsecond heat exchange part is mounted in a vehicle while held in saidair-conditioning case in a state so that, when viewing the second heatexchange part from the side, the angle formed by the longitudinaldirection of said tubes and the vertical direction forms an acute angle,and said liquid storage part is formed inside said inlet side tank partin a region above the inlet side end of said tube by making said secondheat exchange part slanted.
 3. A vehicular air-conditioning system asset forth in claim 1, wherein said liquid storage part is formed bymaking part of the wall forming said inlet side tank part bulge outsidefrom the other parts.
 4. A vehicular air-conditioning system as setforth in claim 1, wherein said first heat exchange part comprises aplurality of tubes stacked together, an inlet side tank part which isconnected to first end sides of said plurality of tubes in thelongitudinal direction and which forms a liquid inlet side, and an exitside tank part which is connected to other end sides of the plurality oftubes in the longitudinal direction and which forms a liquid exit side,an insertion length of said tubes which are inserted inside of saidinlet side tank part of the second heat exchange part is longer than aninsertion length of said tubes which are inserted into said inlet sidetank part of said first heat exchange part, and said liquid storage partis formed inside said inlet side tank part of said second heat exchangepart in a region above inlet side ends of said tubes in the gravitydirection.
 5. A vehicular air-conditioning system as set forth in claim1, wherein when projecting an end opening of a liquid introduction pathintroducing said second liquid to said inlet side tank part of saidsecond heat exchange part in a longitudinal direction of said inlet sidetank part, at least part of the end opening of said liquid introductionpath is positioned other than right under the inlets of said tubes inthe gravity direction.
 6. A vehicular air-conditioning system as setforth in claim 5, wherein at least part of the end opening of saidliquid introduction path is positioned outside from between twoimaginary lines which are drawn from the inside walls of said tubes atthe inlet side ends of said tubes in parallel in the gravity direction.7. A vehicular air-conditioning system as set forth in claim 5, whereinat least part of the end opening of said liquid introduction path ispositioned at an upper side from an imaginary line extending in linewith the inlet side end faces of said tubes.
 8. A vehicularair-conditioning system as set forth in claim 5, wherein a part of 35%or more of the total area of the end opening of said liquid introductionpath is positioned other than right under the inlets of said tubes inthe gravity direction.
 9. A vehicular air-conditioning system as setforth in claim 1, wherein said second heat exchange part is mounted in avehicle while held in said air-conditioning case in a slanted state sothat said second liquid flows from one end side of said inlet side tankpart in a longitudinal direction thereof and so that a top wall of saidinlet side tank part is positioned with one end side of said inlet sidetank part in the longitudinal direction upward in the gravity directioncompared with the other end side.
 10. A vehicular air-conditioningsystem as set forth in claim 1, wherein inside said inlet side tank partof said the second heat exchange part, a flow velocity raising means isprovided for making the flow velocity of the second liquid flowing tosaid inlet side tank part rise.
 11. A vehicular air-conditioning systemas set forth in claim 1, wherein said first heat exchange part comprisesa

plurality of tubes stacked together, an inlet side tank part which isconnected to first end sides of said plurality of tubes in thelongitudinal direction thereof and which forms a liquid inlet side, andan exit side tank part which is connected to other end sides of theplurality of tubes in the longitudinal direction and which forms aliquid exit side, and a channel sectional area of the inlet side tankpart of the second heat exchange part is smaller than the channelsectional area of the inlet side tank part of said first heat exchangepart.
 12. A vehicular air-conditioning system as set forth in claim 1,wherein said first heat exchange part comprises a plurality of tubesstacked together, an inlet side tank part which is connected to firstend side's of said plurality of tubes in a longitudinal directionthereof and which forms a liquid inlet side, and an exit side tank partwhich is connected to other end sides of the plurality of tubes in thelongitudinal direction and which forms a liquid exit side, and a channelsectional area of a liquid introduction path which introduces saidsecond liquid to said inlet side tank part of the second heat exchangepart is smaller than a channel sectional area of a liquid introductionpath which introduces said first liquid to the inlet side tank part ofsaid first heat exchange part.
 13. A vehicular air-conditioning systemcomprising a heating-use heat exchanger which uses a first liquid and asecond liquid with a higher temperature and smaller flow rate than saidfirst liquid as heat sources to heat air blown into a passengercompartment, wherein said heating-use heat exchanger comprises a firstheat exchange part which exchanges heat between said first liquid andsaid blown air, and a second heat exchange part which exchanges heatbetween said second

liquid and said blown air which was heated by said first heat exchangepart, said second heat exchange part comprises a plurality of tubesstacked together, an inlet side tank part which is connected to firstend sides of said plurality of tubes in a longitudinal direction thereofand which forms a liquid inlet side, and an exit side tank part which isconnected to the other end sides of the plurality of tubes in thelongitudinal direction and which forms a liquid exit side, said secondheat exchange part is held in an air-conditioning case so that saidinlet side tank part is positioned at a lower side in a gravitydirection and so that said exit side tank part is positioned at an upperside in a gravity direction, and inside of said inlet side tank part, aflow velocity raising means is provided to raise the flow velocity ofthe second liquid which flows into said inlet side tank part.